[PATCH/RFC] net: Add __napi_sycnhronize() to sync with napi poll

[Stephen Hemminger]

Please don't use double underscore, for this function name. There is no
reason to not make it a normal API call.

The sky2 fix I am working on will use napi_synchronize as well.

--- a/include/linux/netdevice.h	2007-10-16 16:48:20.000000000 -0700
+++ b/include/linux/netdevice.h	2007-10-17 08:29:55.000000000 -0700
@@ -407,6 +407,24 @@ static inline void napi_enable(struct na
 	clear_bit(NAPI_STATE_SCHED, &n->state);
 }
 
+#ifdef CONFIG_SMP
+/**
+ *	napi_synchronize - wait until NAPI is not running
+ *	@n: napi context
+ *
+ * Wait until NAPI is done being scheduled on this context.
+ * Any outstanding processing completes but
+ * does not disable future activations.
+ */
+static inline void napi_synchronize(const struct napi_struct *n)
+{
+	while (test_bit(NAPI_STATE_SCHED, &n->state))
+		msleep(1);
+}
+#else
+# define napi_synchronize(n)	barrier()
+#endif
+
 /*
  *	The DEVICE structure.
  *	Actually, this whole structure is a big mistake.  It mixes I/O